Tested Wi-Fi Adapters:
Wi-Fi Configuration for Debian on Pogoplug
#Add "non-free" repo
echo "deb http://http.debian.net/debian/ wheezy main contrib non-free">>/etc/apt/sources.list
#Update repo
apt-get update
#Install required Wi-Fi packages and common non-free Wi-Fi adapter firmware
apt-get install wireless-tools wpasupplicant usbutils firmware-ralink firmware-realtek firmware-atheros
#Bring up Wi-Fi adapter. If you get an error, try rebooting.
ifconfig wlan0 up
#Scan available Wi-Fi networks
iwlist wlan0 scanning
#Update interfaces file with Wi-Fi configuration
nano /etc/network/interfaces
#Add the following to the end of the /etc/network/interfaces file
#Update "YourWiFiNetworkName" and "YourWiFiPassword" with appropriate values.
#/etc/network/interfaces
#auto wlan0
#iface wlan0 inet dhcp
# wpa-ssid "YourWiFiNetworkName"
# wpa-psk "YourWiFiPassword"
#Restart Networking Service
/etc/init.d/networking restart
#Check if Wi-Fi configuration successful
#Note the IP Address assigned to wlan0
ifconfig
At this point, you should be able to reboot and unplug the Ethernet network cable from the Pogoplug.
Notes: I don't use wireless with my Pogoplugs so have not tested Wi-Fi extensively. If you don't have a stable Wi-Fi connection, you may want to look into a Wi-Fi auto reconnect script. If I find a good script or method for Wi-Fi auto reconnect, I'll post it. If you have a good solution, please share via the comments.
If you lose Wi-Fi connection, plugging in the Ethernet network cable should work, but note that it may take 2-3 minutes for the Pogoplug to pick up a IP Address.
Reference:
https://wiki.debian.org/rtl819x#Debian_7_.22Wheezy.22